Federal law, 26 U.S.C. §5845(a), states that rifles and shotguns must have an overall length of 26 inches. Additionally, many states have similar laws mandating a minimum length of long arms. To correctly measure the overall length for the purpose of determining the legality of a firearm, it must be measured from the furthest point of the rear stock to the most forward point of the barrel along the axis of the firearm.
One problem the present invention addresses is inconsistency of measurement by different people. This can be caused by holding the ruler in a variety of positions resulting in a variety of measurements. Also, measuring the firearm diagonally can cause incorrect measurements. These incorrect measurements can affect the legal ramifications associated with a criminal case.
The present invention assures the firearm is positioned correctly, thus preventing the potential for incorrect measurement. The incorporation of the fixed ruler under the sliding rail assists in accurately measuring the length of a firearm with the ruler being positioned perpendicular with the axis of the firearm.